Aircraft maintenance apparatus and method of maintaining aircraft

ABSTRACT

An apparatus and methods are provided for performing maintenance procedures such as washing, cleaning, deicing, and painting to an aircraft. The apparatus according to an embodiment of the present invention preferably has a mobile base having a plurality of wheel members for allowing the mobile base to travel along surfaces and a plurality of support surface registering members for registering the mobile base to a support surface to inhibit movement of the plurality of wheel members. The apparatus also preferably has a boom member having a proximal end portion rotatably mounted to the mobile base and being movable between a retracted position and an extended position and an aircraft maintenance tool rotatably connected to a distal end portion of the boom member.

RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 09/174,511 filed Oct.16, 1998, now U.S. Pat. No. 6,134,734, the disclosure of which is herebyincorporated by reference in its entirety which is acontinuation-in-part of U.S. patent application Ser. No. 08/786,829,filed on Jan. 21, 1997, now U.S. Pat. No. 5,858,111, and U.S. patentapplication Ser. No. 09/161,610, filed on Sep. 25, 1998, now U.S. Pat.No. 5,979,001, and which are both incorporated herein in theirentireties by reference.

FIELD OF THE INVENTION

The present invention relates to the field of aviation and, moreparticularly, to the maintenance of aircraft.

BACKGROUND OF THE INVENTION

Over the years, various aircraft maintenance equipment has beendeveloped for maintaining various portions of an aircraft. This aircraftmaintenance equipment has included washing, cleaning, deicing, painting,polishing, sanding, grinding, and/or other maintenance functions. Suchsystems conventionally provide an aircraft cleaning or paintingapparatus which has a pair of spaced-apart tracks for positioning anaircraft therebetween and a track base slidably mounted to each track.An example of such a system can be seen in U.S. Pat. No. 5,458,299 byCollins et al. titled “Aircraft Deicing Apparatus”. Other systemsprovide an aircraft cleaning or painting apparatus that has a boompivotally mounted to a slidable support base. Examples of such anapparatus can be seen in U.S. Pat. No. 5,490,646 by Shaw et al. titled“Aircraft Maintenance Robot”, U.S. Pat. No. 5,318,254 by Shaw et al.titled “Aircraft Maintenance Robot”, and U.S. Pat. No. 3,835,498 byArato titled “Craft Washing Plant”. Still other systems provide overheadtracks under which an aircraft or other vehicle passes for providingmaintenance such as painting, cleaning, or deicing. Examples of thistype of system can be seen in French EPO-0341-134 Published PatentApplication by Jonca and U.S. Pat. No. 5,320,121 by Alexanian titled“Vehicle Washing System”.

These conventional aircraft maintenance systems, however, attempt toprovide movement of a washing, cleaning, deicing, painting, polishing,sanding, or grinding apparatus by complex boom type systems which oftenrequire an expensive installation facility which includes extensiveinstallation obstacles to overcome. These systems also often distributethe weight of the apparatus performing the maintenance functions eitherwith the structure, i.e., building, hangar, garage, itself or at asubstantial distance from the aircraft. This operational requirement, inturn, requires the extensive boom-type or robotic-type arms which extendoutwardly from a base to perform the maintenance operation. Theseboom-type arms conventionally carry extensive electronics and can bequite expensive to manufacture. Other problems associated with theseboom-type arms include the risk from damage to the long outwardlyextending arms by moving aircraft, the requirement of complex andexpensive control of the arm at a base a distance away from theaircraft, and the lack of effective control of the arm, e.g., to trackthe contour of the aircraft, and the maintenance tools adjacent theaircraft.

SUMMARY OF THE INVENTION

With the foregoing in mind, the present invention advantageouslyprovides an apparatus and method for maintaining an aircraft thatprovides effective control of maintenance tools adjacent the aircraft.The present invention also advantageously provides an apparatus andmethod to track or follow the contour of the aircraft by providing theweight of the control of the maintenance tool adjacent the aircraft andreducing the problems and risks associated with the use of a longboom-type arm extending outwardly from hangar walls or roofs to providethe maintenance functions. The present invention additionallyadvantageously provides an aircraft maintenance a apparatus and methodwith increased degrees of freedom of movement for movement of amaintenance tool in the X, Y, and Z planes.

More particularly, an apparatus for maintaining an aircraft according toan embodiment of the present invention preferably has a mobile basehaving a plurality of wheel members for allowing the mobile base totravel along surfaces and a plurality of support surface registeringmembers for registering the mobile base to a support surface to inhibitmovement of the plurality of wheel members. The apparatus alsopreferably has a boom member having a proximal end portion rotatablymounted to the mobile base and being movable between a retractedposition and an extended position and an aircraft maintenance toolrotatably connected to a distal end portion of the boom member.

According to another aspect of the present invention, an apparatus formaintaining an aircraft preferably includes a mobile base, a boom memberhaving a proximal end portion rotatably mounted to said mobile base. Theboom member is preferably movable between a retracted position and anextended position. The apparatus also preferably includes an aircraftmaintenance tool rotatably connected to a distal end portion of the boommember.

According to yet another aspect of the present invention, an apparatusfor maintaining an aircraft preferably includes a mobile base includingrotating means for providing rotational movement of the mobile base on asupport surface, a boom member having a proximal end portion rotatablymounted to the mobile base, and an aircraft maintenance tool connectedto a distal end portion of the boom member.

The present invention also provides a maintenance tool such as for anaircraft. The maintenance tool preferably includes a tool housing, apair of roll members having at least portions thereof mounted in thetool housing, and driving means connected to the tool housing forrotatably driving the pair of roll members in opposite rotationaldirections.

Another embodiment of a maintenance tool such as for maintaining anaircraft preferably includes a tool housing, a nozzle connected to thetool housing, and nozzle moving means connected to the tool housing forpivotally moving the nozzle in a first plane and for pivotally movingthe nozzle in a second different plane.

The present invention also includes a mobile vehicle which preferablyhas a base having at least upper and lower portions and a driveconnected to the base. A plurality of wheels are connected to a lowerportion of the base and are also each connected to the drive so that theplurality wheels responsively move the base in a plurality of differentdirections, e.g., radial directions, responsive to the drive. The lowerportion of the base includes a plurality of recessed regions into eachof which one of the plurality of wheels is mounted. Each of the wheelsof the vehicle preferably include a hub and a plurality of rollermembers dispersed around the hub. Each of the plurality of wheels isdrivable or movable responsive to the drive in a selected directionindependent of each of the other plurality of wheels. Also, a pluralityof leveling legs can be connected to the base for leveling the base inselected positions. The plurality of leveling leg are preferably beingmovable between retracted and extended positions.

The present invention also provides a method of maintaining an aircraft.The method preferably includes rotating a boom member connected to abase, extending the boom member from a retracted position, and rotatingan aircraft maintenance tool connected to the boom member duringoperation of a maintenance procedure upon an aircraft. The method canalso include rotating the base about a support surface.

Another method according to the present invention preferably includes amethod of treating a surface. The method preferably includes the stepsof providing a pair of roll members having surface treating meansassociated therewith and rotationally driving the pair of roll membersin opposite rotational directions. The method can also include each ofthe pair of roll members having a roller and a roller cover. The rollercover includes a plurality of surface contact members associatedtherewith. Also, each of the rollers can advantageously be inflatable,and the method further including inflating each of the inflatablerollers.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the features, advantages, and benefits of the present inventionhaving been stated, others will become apparent as the descriptionproceeds when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is an environmental perspective view of an aircraft maintenanceapparatus operating on an airplane in a hangar according to a firstembodiment of the present invention;

FIG. 2 is a perspective view of an aircraft maintenance apparatus in anextended position according to a first embodiment of the presentinvention and illustrating portions of an airplane in broken lines;

FIG. 3 is side elevational view of an aircraft maintenance apparatus inan extended position according to a second embodiment of the presentinvention;

FIG. 4 is a side elevational view of an aircraft maintenance apparatusin a retracted position according to a first embodiment of the presentinvention;

FIG. 5 is a top plan view of an aircraft maintenance apparatus accordingto a first embodiment of the present invention;

FIG. 6 is a perspective view of an aircraft maintenance apparatusaccording to a second embodiment of the present invention;

FIG. 7 is a perspective view of an aircraft maintenance apparatus havinga transport vehicle and a separable base according to a first embodimentof the present invention;

FIG. 8 is a fragmentary side elevational view of an aircraft maintenanceapparatus and an airplane according to an embodiment of the presentinvention;

FIG. 9 is a side elevational view of a maintenance tool of an aircraftmaintenance apparatus according to an embodiment of the presentinvention;

FIG. 10 is an exploded perspective view of a maintenance tool of anaircraft maintenance apparatus according to an embodiment of the presentinvention;

FIG. 11 is an environmental top plan view of a plurality of aircraftmaintenance apparatuses according to an embodiment of the presentinvention;

FIG. 12 is a top plan view of a plurality of aircraft maintenanceapparatuses operating on an airplane according to an embodiment of thepresent invention;

FIG. 13 is a fragmentary perspective view of a deicing tool of anaircraft maintenance apparatus according to a third embodiment of thepresent invention;

FIG. 14 is a side elevational view of a deicing tool of an aircraftmaintenance apparatus of FIG. 13 according to the present invention;

FIG. 15 is a top plan view of a deicing tool of an aircraft maintenanceapparatus of FIG. 11 according to the present invention;

FIG. 16 is a perspective view of a mobile base portion of an aircraftmaintenance apparatus according to the present invention;

FIG. 17 is a perspective view of an aircraft maintenance apparatushaving a plurality of auxiliary maintenance modules added to a mobilebase portion thereof according to the present invention;

FIG. 18 is a perspective view of an aircraft maintenance apparatushaving an aircraft maintenance module added thereto according to thepresent invention;

FIG. 19 is a perspective view of an aircraft maintenance apparatushaving another embodiment of an aircraft maintenance module according tothe present invention;

FIG. 20 is an exploded side elevational view of a mobile base portionhaving a plurality of maintenance modules adapted to be connectedthereto of an aircraft maintenance apparatus according to the presentinvention;

FIG. 21 is a perspective view of an aircraft maintenance apparatushaving another embodiment of a maintenance tool according to the presentinvention;

FIG. 22 is a perspective view of an aircraft maintenance tool of anaircraft maintenance apparatus according to the present invention; and

FIG. 23 is a perspective view of an aircraft maintenance apparatushaving yet another embodiment of a maintenance tool according to thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings which illustrated preferredembodiments of the invention. This invention may, however, be embodiedin many different forms and should not be construed as limited to theillustrated embodiments set forth herein. Rather, these illustratedembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. Like numbers refer to like elements throughout, andprime and double prime notation are used to indicate similar elements inalternative embodiments.

FIGS. 1 and 11-12 illustrate environmental views of an aircraft Amaintenance apparatus 30 according to a first embodiment of the presentinvention. The aircraft A as illustrated is generally mounted to orrolls along a support surface or floor F. The floor F of a maintenancehangar, warehouse, or other maintenance region, for example, ispreferably slanted toward a drain for collecting waste fluid run-offfrom the washing, de-icing, painting, or other maintenance process. Theapparatus 30 preferably has the capability to perform maintenance tasksalong the fuselage, wings, tail, and nose sections of the aircraft.

An apparatus 30 for maintaining an aircraft A according to an embodimentof the present invention preferably has a mobile base 40 having aplurality of wheel members 50 for allowing the mobile base 40 to travelalong surfaces F and a plurality of support surface registering members45 for registering the mobile base 40 to a support surface to inhibitmovement of the plurality of wheel members 50. The plurality of supportsurface registering members 45 preferably each include a leveling leg 46which extends and retracts generally in a vertical plane. Theregistering members 45 also can extend and retract in transverse orhorizontal planes, as illustrated.

The mobile base 40 can also advantageously include a plurality ofauxiliary maintenance modules, e.g., fluid tanks 49 for supplying fluidto one or more maintenance tools associated with the apparatus 30. Theapparatus 30 also preferably has a boom member 60 having a proximal endportion rotatably mounted to the mobile base 40 and being movablebetween a retracted position and an extended position and at least oneaircraft maintenance tool 80 rotatably connected to a distal end portionof the boom member 60.

FIG. 2 illustrates an operator O remotely Operating the apparatus 30from a remote operator booth B 25 according to a first embodiment of thepresent invention. As illustrated in FIG. 6, the mobile base 40′ of asecond embodiment of an apparatus 30′ can further have an operator cab Cfor positioning an operator O therein and for operating the apparatus30′ from the mobile base 40′. The mobile base 40′ also preferablyincludes at least one drive 42, e.g., an engine and a drive assembly,for driving the wheels 50′ of the mobile base 40′.

FIGS. 2-5 and 8 illustrate structural features of the boom member 60 andthe operation of the boom member 60, the mobile base 40, and themaintenance tool 80. Each of the plurality of wheel members 50 of themobile base 40 includes an omni-directional vehicle wheel for providingat least forward, lateral, diagonal, and rotational motion of the mobilebase 40 (see FIG. 5 arrows). The mobile-base 40 also has a rotatableplatform, 43 positioned along an upper end portion-thereof. Theplurality of support surface registering members 45 each preferablyincludes a support surface contact member or legs 46 and a hydraulicengaging member 48 connected to the support surface contact member 46for hydraulically engaging the support surface contact member 46 withthe support surface F.

The boom member 60 preferably includes a first-boom arm 61 which has aproximal end portion pivotally connected to the rotatable platform 43 ofthe mobile base 40 and which has a retracted position (see FIG. 4) andan extended position (see FIG. 3), e.g., by the use of a piston andcylinder connector assembly. A second boom arm 63 has a proximal endportion mounted to the first boom arm 61 and likewise has a retractedposition and an extended position. A third boom arm 65 has a medialportion pivotally mounted to the distal end portion of the second boomarm 63 and also has a retracted position and an extended position. Theboom member 60 further preferably includes yet a fourth boom arm 67having a proximal end portion rotatably mounted to a distal end portionof the third boom arm 65.

As perhaps best illustrated in FIG. 8, the fourth boom arm 67 includes aplurality of arm links. The plurality of arm links include a first armlink 72 having a proximal end rotatably connected to the distal endportion of the third boom arm 65, a second arm link 74 having a proximalend pivotally connected to the distal end of the first arm link 72, athird arm link 76 having a proximal end portion rotatably or pivotallyconnected to the second arm link 74, and a fourth arm link 78 having aproximal end rotatably connected to the distal end of the third arm link76.

As perhaps best illustrated in FIGS. 8-10, the present invention alsoprovides a maintenance tool 80 such as for an aircraft A. Themaintenance tool 80 preferably includes a tool housing 81, a pair ofroll members 83, 84 having at least portions thereof mounted in the toolhousing 81, and driving means, e.g., a motor 86, drive rolls or shaftsand drive chains, connected to the tool housing 81 for rotatably drivingthe pair of roll members 83, 84 in opposite rotational directions. Theroll members 83, 84, for example, can include bristles, strips of softcloth, or other brush-like members for cleaning or buffing the outersurface of an aircraft A. The tool 80 also preferably includes asuctioning wiper member 88 which is preferably connected to a fluidcollection hose 26. The roll members 83, 84 or other portions of thetool 80 are also preferably connected to a,fluid supply hose 28.

As perhaps best illustrated in FIGS. 13-15, another embodiment of amaintenance tool 80′ such as for maintaining an aircraft A preferablyincludes a tool housing 81′, a nozzle 85 connected to the tool housing81′, and nozzle moving means 87 connected to the tool housing 811 forpivotally moving the nozzle 85 in a first plane P1 (see FIG. 14) and forpivotally moving the nozzle 85 in a second different plane P2 (see FIG.15).

FIGS. 7 and 16-23 illustrate another embodiment of a mobile base 38 ormobile vehicle 40′ of an aircraft maintenance apparatus 30 according tothe present invention. Notice that the base 38 can be separable from thegeneral platform of the vehicle 40′ as shown in FIG. 7. It will beunderstood by those skilled in the art, however, that the mobile vehicle40′ can also advantageously be used for other operations such as missiletransport, fire fighting operations, or aircraft towing operations. Themobile vehicle 40′ preferably includes abase 38 having at least upperand lower portions and a drive 42′ connected to the base 38. A pluralityof wheels 50′ are connected to a lower portion of the base 38 and arealso each connected to the drive 42′ so that the plurality wheels 50′responsively move the base 38 a plurality of different directions, e.g.,radial directions and other directions as previously. described,responsive to the drive 42′. The lower portion of the base 38 includes aplurality of recessed regions 41 into each of which one of the pluralityof wheels 50′ is mounted. Each of the wheels 50′ of the vehicle 40′preferably include a hub 52 and a plurality of roller members 54dispersed around the hub 52. Each of the plurality of wheels 50′ isdrivable or movable responsive to the drive 42′ in a selected directionindependent of each of the other plurality of wheels 50′.

Additionally, a plurality of auxiliary maintenance modules 49′ areconnected to the upper portion of the base 38. The plurality ofauxiliary maintenance modules 49′ are positioned along peripheral edgesof the base 38′. At least one main maintenance module 58 is preferablyconnected to the upper portion of the base 38 and has a maintenance toolconnected thereto. The at least one main maintenance module 58 furtherincludes a module base portion 57, 57′, a boom arm portion 60″ rotatablyconnected to the module base portion 57, 57′, and the maintenance tool80″, 80′″ being connected to the boom arm portion 60″. The boom armportion 60″, 60′″, 60″″, is preferably extendable between retracted andextended positions. Alternatively, or in addition thereto, retractableand extendable connecting means, e.g., preferably provided by themovable cross members 51 as illustrated in FIG. 19, can be positionedbetween and connected to the upper portion of the base 38 and the mainmaintenance module 58 for retracting and extending the main maintenancemodule 58. At least either one of the plurality of auxiliary maintenancemodules 49 or the main maintenance module 58 includes a chamber 6 havingat least one maintenance fluid positioned therein. The fluid ispreferably a deicing or washing fluid, but other maintenance fluids canbe used as well as understood by those skilled in the art. Further, themobile vehicle 40′ can also advantageously include a plurality ofleveling legs 46′ connected to the base 38 for leveling the base 38 inselected positions, e.g., along support surfaces which are not level soas to balance and adjust the base 38 and/or boom arm 60′. The pluralityof leveling legs 46′ are preferably movable between retracted andextended positions as previously described. These alternate embodimentsof the apparatus 30, 30′ and the associate elements connected theretofurther advantageously illustrate the modularity and interchangeabilityof the components of the apparatus 30, 30′.

As illustrated in FIGS. 1-23, the present invention also providesmethods of maintaining an aircraft A. A method preferably includesrotating a boom member 60 connected to a base 40, extending the boommember 60 from a retracted position, and rotating an aircraftmaintenance tool 80 connected to the boom member 60 during operation ofa maintenance procedure upon an aircraft A. The method can also includerotating the base 40 about a support surface. The method can alsoadvantageously include moving the base 40 in at least forward, lateral,diagonal, and rotational directions about the support surface F,supplying fluid to the maintenance tool 80, and suctioning fluid fromthe maintenance tool 80 (see FIGS. 8-9).

The method can further include the base 40 further having a plurality ofsupport surface registering members 45 each including a support surfacecontact member or leg 46 and a hydraulic engaging member 48 connected tothe support surface contact member 46. The method then includeshydraulically engaging the support surface contact member 46 with thesupport surface F. The method can also include the aircraft maintenancetool 80 having at least a pair of roll members 83, 84, and the methodfurther including rotatably driving the pair of roll members 83, 84 inopposite rotational directions. Additionally, the base 40, the boommember 60, and the maintenance tool 80 can be either remotely operatedor operating with an operator O positioned on the base 40 (see FIGS.2-3).

Another method according,to the present invention preferably includes amethod of treating a surface. The method preferably includes the stepsof providing a pair of roll members 83, 84 having surface treating means87 associated therewith and rotationally driving the pair of rollmembers 83, 84 in opposite rotational directions. The method can alsoinclude each of the pair-of roll members 83, 84 having a roller and aroller cover. The roller cover includes a plurality of surface contactmembers associated therewith. Also, each of the rollers canadvantageously be inflatable, and the method further including inflatingeach of the inflatable rollers.

The method can also advantageously include supplying fluid to an itemfor cleaning thereof with the pair of roll members 83, 84 and suctioningfluid from an item adjacent the maintenance tool 80. The step ofsuctioning fluid includes suctioningly wiping fluid positioned betweenthe pair of roll members 83, 84 (see FIG. 9).

In the drawings and specification, there have been disclosed a typicalpreferred embodiment of the invention, and although specific terms areemployed, the terms are used in a descriptive sense only and not forpurposes of limitation. The invention has been described in considerabledetail with specific reference to these illustrated embodiments. It willbe apparent, however, that various modifications and changes can be madewithin the spirit and scope of the invention as described in theforegoing specification and as defined in the appended claims.

That which is claimed:
 1. A mobile vehicle, the mobile vehiclecomprising: a base having upper and lower portions, the lower portionincluding a plurality of recessed regions into each of which one of aplurality of wheels is mounted; a drive connected to said base; and aplurality of wheels each of which is drivable responsive to said drivein a selected direction independent of each of the other plurality ofwheels, each said plurality of wheels being connected to a lower portionof said base, positioned in one of the plurality of recessed regions,and connected to said drive so that said plurality of wheelsresponsively move said base in at least three different directionsresponsive to said drive, each of said wheels including a hub and aplurality of roller members dispersed around said hub.
 2. A mobilevehicle as defined in claim 1 further comprising a plurality ofauxiliary maintenance modules connected to the upper portion of saidbase.
 3. A mobile vehicle as defined in claim 2 wherein a plurality ofauxiliary maintenance modules are positioned along peripheral edges ofsaid base.
 4. A mobile vehicle as defined in claim 3 further comprisingat least one maintenance module connected to the upper portion of saidbase and having a maintenance tool connected thereto.
 5. A mobilevehicle as defined in claim 4 wherein said at least one maintenancemodule further includes a module base portion, a boom arm portionrotatably connected to said module base portion, and the maintenancetool being connected to said boom arm portion, said boom arm portionbeing extendable between retracted and extended positions.
 6. A mobilevehicle as defined in claim 4, further comprising retractable andextendable connecting means positioned between and connected to theupper portion of said base and said main maintenance module for reactingand extending said main maintenance module.
 7. A mobile vehicle asdefined in claim 4, wherein at least either one of said plurality ofauxiliary maintenance modules or said main maintenance module includes,a chamber having at least one maintenance fluid positioned therein.
 8. Amobile vehicle as defined in claim 1, further comprising a plurality ofleveling legs connected to said base for leveling said base in selectedpositions, said plurality of leveling legs being movable betweenretracted and extended positions.
 9. A mobile vehicle, the mobilevehicle comprising: a base having at least upper and lower portions, theupper portion of said base including a maintenance module having amodule base portion and a boom arm connected to the module base portion;a drive connected to said base; and a plurality of wheels connected to alower portion of said base and connected to said drive so that saidplurality of wheels responsively move said base in at least threedifferent directions responsive to said drive, each of said wheelsincluding a hub and a plurality of roller members dispersed around saidhub.
 10. A mobile vehicle as defined in claim 9, wherein said boom armportion comprises: a first boom arm having a proximal end portionpivotally connected to a rotatable platform of the base, and haveretracted and extended positions; a second boom arm having a proximalend portion mounted to said first boom arm and having retracted andextended positions; a third boom arm having a medial portion pivotallymounted to the distal end portion of said second boom arm and havingretracted and extended positions; and a fourth boom arm having aproximal end portion rotatably mounted to a distal end portion of saidthird boom arm.
 11. A mobile vehicle as defined in claim 10, whereinsaid fourth boom arm further comprises a plurality of arm links, theplurality of arm links including, the first arm link having a proximalend rotatably connected to the distal end portion of the third boom arm,the second arm link having a proximal end pivotally connected to thedistal end of said first arm link, the third arm link having proximalend portions pivotally connected to said second arm link, and a fourtharm link having a proximal end pivotally connected to the distal end ofsaid third arm link.
 12. A mobile vehicle, the mobile vehiclecomprising: a base having at least upper and lower portions; amaintenance tool including a tool housing connected to said base; anozzle connected to said tool housing; nozzle moving means connectedsaid tool housing for pivotally moving said nozzle in a first plane andfor pivotally moving said nozzle in a second different plane; a driveconnected to said base; and a plurality of wheels connected to a lowerportion of said base and connected to said drive so that said pluralityof wheels responsively move said base in at least three differentdirections responsive to said drive, each of said wheels including a huband a plurality of roller members dispersed around said hub.